Abstract
The structural phase transition and metallization of the simple alkali iodide, sodium iodide (NaI) is investigated through their band structures. The band structure, density of states (DOS) and total energy are computed as a function of volume for both NaCl and CsCl phases using the full potential linear muffin-tin orbital (FP-LMTO) method. The phase transition pressure (PT) and the corresponding reduced volume (VT) estimated in our calculation are 0.038 Mbar and 0.89 respectively. The metallization pressure PM is 2.6259 Mbar and the corresponding reduced volume (VM) is 0.36. The results of the metallization pressure in NaI are compared with that of other alkali iodide spotassium iodide (KI) and RbI. It is found, that the charge transfer from s and p states to the d state will cause metallization and the metallization pressure increases with a decrease of the lattice constant. It is also confirmed that the metallization and structural phase transition do not occur simultaneously in ionic compounds.
Highlights
The physical properties of materials undergo a variety of changes when they are subjected to high pressure [1]
Vo is the experimental equilibrium volume corresponding to the experimental equilibrium lattice constant
As a result the widths of the valence and empty conduction bands increase. These changes lead to the narrowing and closing of band gaps
Summary
The physical properties of materials undergo a variety of changes when they are subjected to high pressure [1]. Already twenty three new elemental superconductors were found at high pressure. In this list new compounds are being included. One such compound is the simple ionic salt CsI [3]. This material is a testing ground both for photo converters [3].The metallization in CsI is experimentally
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